The realization that defined tumor antigens can serve as targets for recognition by T lymphocytes has motivated attempts at developing and optimizing immunologic therapies for the treatment of cancer. This excitement has been reinforced by the success of two humanized monoclonal antibodies, Herceptin and Rituxan, for the treatment of breast cancer and lymphoma, respectively, as well as the approval of two cytokines, interleukin-2 and interferon-alpha, for the treatment of melanoma. The development of new immune-based therapies, such as cancer vaccines and novel cytokines, and the elucidation of the mechanism of action of currently available treatments, require careful monitoring of scientific endpoints to determine the optimal biologically active dose and schedule of these agents. The purpose of the Human Immunologic Monitoring Facility is to perform such assays in the context of clinical trials in cancer patients. This service enables a range of clinical cancer researchers, who may not themselves have the expertise or laboratory commitment to carry out these assays, to measure Immunotherapy Group as it develops cancer treatment strategies involving vaccines, monoclonal antibodies, cytokines, and cell-based therapies. immunologic endpoints in participating study subjects. Assays currently performed include measurement of T cell cytokine production, proliferation, and cytolytic activity; serum cytokine content; flow cytometric analysis of hematopoietic and T cell subsets; induced intracellular cytokines by flow cytometry; and RT-PCR analysis of tumor antigen gene expression. Preparation of peptide-based cancer vaccines is also performed. New assays are under development that will incorporate the latest techniques and enable important new scientific questions to be asked in the clinical setting. In sum, this facility provides clinical trial laboratory support for our Cancer